Security is fast becoming an important issue. Is has always been an issue for everybody to protect his belongings. It is also well known that with the proliferation of computers and computer networks into all aspects of business and daily life—financial, medical, education, government, and communications—the concern over secure file access is growing. Using passwords is a common method of providing security. Password protection and/or combination type locks are employed for computer network security, automatic teller machines, telephone banking, calling cards, telephone answering services, houses, and safes. These systems generally require the knowledge of an entry code that has been selected by a user or has been preset.
Preset codes are often forgotten, as users have no reliable method of remembering them. Writing down the codes and storing them in close proximity to an access control device (i.e., the combination lock) results in a secure access control system with a very insecure code. Alternatively, the nuisance of trying several code variations renders the access control system more of a problem than a solution.
Password systems are known to suffer from other disadvantages. Usually, a user specifies passwords. Most users, being unsophisticated users of security systems, choose passwords, which are relatively insecure. As such, many password systems are easily accessed through a simple trial and error process. It is well known to those skilled in the art that a security access system that provides substantially secure access and does not require a password or access code is a biometric identification system. A biometric identification system accepts unique biometric information from a user and identifies the user by matching the information against information belonging to registered users of the system. As a matter of fact, the ultimate method of personal identification is not a card, which can be lost, loaned or stolen, nor a number code, which can be discovered; but an unchangeable, non-transferable and indisputably unique characteristic of the person himself, in the form of biometric information such as a fingerprint. Fingerprint sensing and matching is a reliable technique for personal identification and/or verification.
In a fingerprint input transducer or sensor, the finger under investigation is usually pressed against a flat surface, such as a side of a glass plate; the ridge and valley pattern of the finger tip is sensed by a sensing means such as an interrogating light beam.
Today, fingerprint characterization is well known and can involve many aspects of fingerprint analysis. U.S. Pat. No. 4,353,056 in the name of Tsikos issued Oct. 5, 1982, discloses a fingerprint sensor that uses a capacitive sensing approach. Various optical devices are known which employ prisms upon which a finger whose print is to be identified is placed. The prism has a first surface upon which a finger is placed, a second surface disposed at an acute angle to the first surface through which the fingerprint is viewed and a third illumination surface through which light is directed into the prism. In some cases, the illumination surface is at an acute angle to the first surface, as seen for example, in U.S. Pat. Nos. 5,187,482 and 5,187,748. In other cases, the illumination surface is parallel to the first surface, as seen for example, in U.S. Pat. Nos. 5,109,427 and 5,233,404.
Even though the use of fingerprint identification devices increases the security in controlling more tightly building-access or information-access of individuals to buildings, rooms, and devices such as computer terminals, they are not one hundred percent flawless. Indeed, it is known that the biometric identification process of providing enrollment samples, characterization of the samples and storage in a template associated with the sample for future comparisons results in different enrollment templates for a same person when repeated. Depending upon the result of the comparison between a fingerprint and a template associated with the samples of the fingerprint, a user is identified or is rejected. It is understandable that with such a system, one fingerprint used for identifying an individual, the rate of false rejection and/or false acceptance is dependent upon the chosen algorithm and upon a quality of the provided fingerprint for use with the algorithm.
Furthermore, enrollment biometric templates must be stored in a computer system and must be accessible for allowing comparison with a newly provided fingerprint imaged by the biometric device; if the level of security and accuracy in the identification process is enhanced, further templates associated with further samples associated with the same individual must also be stored. More importantly, a newly provided fingerprint image is substantially different than the enrollment sample images because the position of the fingertip on the platen of a fingerprint imager or the pressure applied thereon is slightly different from application to application.
Finally, once a user is identified, the system retrieves from memory a password associated with the identification for provision to an application. The password so retrieved is subject to security attacks and might be detected because it is stored somewhere on the system itself or transmitted between systems.